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Spark plugs


MarkBzero

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I have just started to play with nitrous and for higher powered jets I need to retard the ignition and fit colder spark plugs with 3 earth pins.

Always fitted OEM parts so how do I find colder spark plugs with 3 earth pins for ST170 engine?

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1 hour ago, theduck said:

Not sure why the need for 3 earth pins? 

From what I can see the standard plug for st170 is NGK PLTR6A-10G and the upgrade plug is NGK ILTR6A-13G

The instructions suggest a single earth pin can get very hot and cause pre-ignition, 3 pin earth spreads the heat and less likely to cause ignition prematurely.

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Would have thought heat would be more of an issue in boosted setups than in a nitrous setup. Doesn’t the nitrous have a cooling effect? Might be worth seeing if you can speak to any of the drag racing guys who run nitrous, see if the 3 pronged plug thing is a common recommendation. 

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22 hours ago, theduck said:

If you are using copper plugs rather than fancy platinum etc, then in the NGK range just go for the next number up, so as an example a standard pinto plug is APR6FS but the next step colder is APR7FS

I thought it was the other way round, the larger the number the hotter the plug, so a 7 is hotter than a 6, but happy to be wrong

 

Edit I'm wrong I'll go stand in the corner

https://www.ngkntk.in/ngk-technology/importance-of-heat-range/

Edited by phaeton
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